Pyrimidine derivatives useful as selective cox-2 inhibitors

ABSTRACT

The invention provides the compounds of formula (I) in which: R 1  is selected from the group consisting of H, C 1-6 alkyl, C 1-2 alkyl substituted by one to five fluorine atoms, C 3-6 alkenyl, C 3-10 cycloalkylC 0-6 alkyl, C 4-12 bridged cycloalkyl, A(CR 4 R 5 ) n  and b(CR 4 R 5 ) n ; R 2  is C 1-2 alkyl substituted by one to five fluorine atoms; R 3  is selected from the group consisting of C 1-6 alkyl, NH 2  and R 7 CONH; R 4  and R 5  are independently selected from H or C 1-6 alkyl; A is an unsubstituted 5- or 6-membered heteroaryl or an unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a 6-membered aryl substituted by one or more R 6 ; R 6  is selected from the group consisting of halogen, C 1-6 alkyl, C 1-6 alkyl substituted by one or more fluorine atoms, C 1-6 alkoxy, C 1-6 alkoxy substituted by one or more F, NH 2 SO 2  and C 1-6 alkylSO 2 ; B is selected from the group consisting of Formula (i) and (ii) and where (iv) defines the point of attachment of the ring; R 7  is selected from the group consisting of H, C 1-6 alkyl, C 1-6 alkoxy, C 1-6 alkylOC 1-6 alkyl, phenyl, HO 2 CC 1-6 alkyl, C 1-6 alkylOCOC 1-6 alkyl, C 1-6 alkylOCO, H 2 C 1-6 alkyl, C 1-4 alkylOCONHC 1-6 alkyl and C 1-6 alkylCONHC 1-6 alkyl; and n is 0 to 4. Compounds of formula (I) are potent and selective inhibitors of COX-2 and are of use in treatment of the pain, fever and inflammation of variety of conditions and diseases.

This invention relates to pyrimidine derivatives, to processes for theirpreparation, to pharmaceutical compositions containing them and to theiruse in medicine.

The enzyme cyclooxygenase (COX) has recently been discovered to exist intwo isoforms, COX-1 and COX-2. COX-1 corresponds to the originallyidentified constitutive enzyme while COX-2 is rapidly and readilyinducible by a number of agents including mitogens, endotoxin, hormones,cytokines and growth factors. Prostaglandins generated by the action ofCOX have both physiological and pathological roles. It is generallybelieved that COX-1 is largely responsible for the importantphysiological functions such as maintenance of gastrointestinalintegrity and renal blood flow. In contrast the inducible form, COX-2,is believed to be largely responsible for the pathological effects ofprostaglandins where rapid induction of the enzyme occurs in response tosuch agents as inflammatory agents, hormones, growth factors andcytokines. A selective inhibitor of COX-2 would therefore haveanti-inflammatory, anti-pyretic and analgesic properties, without thepotential side effects associated with inhibition of COX-1. We have nowfound a novel group of compounds which are both potent and selectiveinhibitors of COX-2.

The invention thus provides the compounds of formula (I)

in which:

-   R¹ is selected from the group consisting of H, C₁₋₆alkyl, C₁₋₂alkyl    substituted by one to five fluorine atoms, C₃₋₆alkenyl, C₃₋₆alkynyl,    C₃₋₁₀cycloalkylC₀₋₆alkyl, C₄₋₁₂bridged cycloalkyl, A(CR⁴R⁵)_(n) and    B(CR⁴R⁵)_(n);-   R² is C₁₋₂alkyl substituted by one to five fluorine atoms;-   R³ is selected from the group consisting of C₁₋₆alkyl, NH₂ and    R⁷CONH;-   R⁴ and R⁵ are independently selected from H or C₁₋₆alkyl;-   A is an unsubstituted 5- or 6-membered heteroaryl or an    unsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a    6-membered aryl substituted by one or more R⁶;-   R⁶ is selected from the group consisting of halogen, C₁₋₆alkyl,    C₁₋₆alkyl substituted by one more fluorine atoms, C₁₋₆alkoxy,    C₁₋₆alkoxy substituted by one or more F, NH₂SO₂ and C₁alkylSO₂;-   B is selected from the group consisting of    where    defines the point of attachment of the ring;-   R⁷ is selected from the group consisting of H, C₁₋₆alkyl,    C₁₋₆alkoxy, C₁₋₆alkylOC₁₋₆alkyl, phenyl, HO₂CC₁₋₆alkyl,    C₁₋₆alkylOCOC₁₋₆alkyl, C₁₋₆alkylOCO, H₂NC₁₋₆alkyl,    C₁₋₆alkylOCONHC₁₋₆alkyl and C₁₋₆alkylCONHC₁₋₆alkyl; and-   n is 0 to 4.

The term halogen is used to represent fluorine, chlorine, bromine oriodine.

The term ‘alkyl’ as a group or part of a group means a straight orbranched chain alkyl group, for example a methyl, ethyl, n-propyl,i-propyl, n-butyl, s-butyl or t-butyl group.

The term 5-membered heteroaryl means a heteroaryl selected from thefollowing:

The term 6-membered heteroaryl means a heteroaryl selected from thefollowing:

The term 6-membered aryl means:

It is to be understood that the present invention encompasses allisomers of the compounds of formula (I) and their pharmaceuticallyacceptable derivatives, including all geometric, tautomeric and opticalforms, and mixtures thereof (e.g. racemic mixtures). In particular whenthe ring B lacks a plane of symmetry the compounds of formula (I)contain a chiral centre as indicated therein by the asterisk *.Furthermore, it will be appreciated by those skilled in the art thatwhen R⁴ and R⁵ in formula (I) are different the corresponding compoundscontain at least one chiral centre, by virtue of the asymmetric carbonatom defined thereby, and that such compounds exist in the form of apair of optical isomers (i.e. enantiomers).

In one aspect of the invention R¹ is selected from the group consistingof H, C₁₋₆alkyl, C₁₋₂alkyl substituted by one to five fluorine atoms,C₃₋₆alkenyl, C₃₋₆alkynyl, C₃₋₁₀cycloalkylC₀₋₆alkyl, C₄₋₁₂bridgedcycloalkyl and B(CR⁴R⁵)_(n);

In another aspect of the invention R¹ is C₁₋₆alkyl or C₁₋₂alkylsubstituted by one to five fluorine atoms. In another aspect R¹ isC₂₋₆alkyl (e.g. n-butyl).

In another aspect of the invention R¹ is C₃₋₁₀cycloalkylC₀₋₆alkyl, suchas C₃₋₁₀cycloalkyl (e.g. cyclopentyl or cyclohexyl). In another aspectR¹ is C₃₋₁₀cycloalkylmethyl, such as C₃₋₇cycloalkylmethyl (e.g.cyclopentylmethyl).

In another aspect of the invention R¹ is A(CR⁴R⁵)_(n).

In another aspect of the invention R² is CHF₂, CH₂F or CF₃. In anotheraspect R² is CF₃.

In another aspect of the invention R³ is C₁₋₆alkyl, such as C₁₋₃alkyl(e.g. methyl).

In another aspect of the invention R⁴ and R⁵ are independently selectedfrom H or methyl. In another aspect R⁴ and R⁵ are both H.

In another aspect of the invention A is selected from the groupconsisting of

where

defines the point of attachment of the ringand A is unsubstituted or substituted by one or two R⁶.

In another aspect of the invention R⁶ is selected from the groupconsisting of halogen (e.g. F), C₁₋₃alkyl (e.g. methyl), C₁₋₃alkylsubstituted by one to three fluorine atoms (e.g. CF₃), and C₁₋₃alkoxy(e.g. methoxy).

In another aspect of the invention R⁷ is selected from the groupconsisting of C₁₋₆alkyl (e.g. ethyl), phenyl and aminomethyl.

In another aspect of the invention n is 1 to 4.

In another aspect of the invention n is 0 to 2 (e.g. 0).

It is to be understood that the invention covers all combinations ofparticular aspects of the invention as described hereinabove.

Within the invention there is provided one group of compounds of formula(I) (group A) wherein: R¹ is C₁₋₆alkyl (e.g. n-butyl); R² is CF₃; and R³is C₁₋₆alkyl, such as C₁₋₃alkyl (e.g. methyl).

Within the invention there is provided another group of compounds offormula (I) (group B) wherein: R¹ is C₃₋₁₀cycloalkylC₀₋₆alkyl, such asC₃₋₁₀cycloalkyl (e.g. cyclopentyl or cyclohexyl); R² is CF₃; and R³ isC₁₋₆alkyl, such as C₁₋₃alkyl (e.g. methyl).

Within the invention there is provided another group of compounds offormula (I) (group C) wherein: R¹ is C₃₋₁₀cycloalkylmethyl, such asC₇cycloalkylmethyl (e.g. cyclopentylmethyl); R² is CF₃; and R³ isC₁₋₆alkyl, such as C₁₋₃alkyl (e.g. methyl).

Within the invention there is provided another group of compounds offormula (I) (group D) wherein: R¹ is A(CR⁴R⁵)_(n); R² is CF₃; R³ isC₁₋₆alkyl, such as C₁₋₃alkyl (e.g. methyl); R⁴ and R⁵ are independentlyselected from H or methyl; A is selected from the group consisting of

and A is unsubstituted or substituted by one or two R⁶; R⁶ is selectedfrom the group consisting of halogen (e.g. F), C₁₋₃alkyl (e.g. methyl),C₁₋₃alkyl substituted by one to three fluorine atoms (e.g. CF₃), andC₁₋₃alkoxy (e.g. methoxy); and n is 0 to 2 (e.g. 0).

Within group D, there is provided a further group of compounds (groupD1) wherein: R¹ is A(CR⁴R⁵)_(n); R² is CF₃; R³ is methyl; R⁴ and R⁵ areboth H; A is selected from the group consisting of

and A is unsubstituted or substituted by one or two R⁶; R⁶ is selectedfrom the group consisting of fluorine, chlorine, methyl, CF₃ andmethoxy; and n is 0 or 1.

In a preferred aspect the invention provides the following compounds:

-   2-(4-fluorophenoxy)[(methylsulfonyl)phenyl]-6](trifluoromethyl)pyrimidine;-   2-(4-methoxyphenoxy)₄-[4-(methylsulfonyl)phenyl]-6-trifluoromethyl)pyrimidine;-   2-butoxy-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine;-   2-[(5-chloropyridin-3-yl)oxy]-4-[4-(methylsulfony)phenyl]-6-(trifluoromethyl)pyrimidine;-   2-(cyclohexyloxy)-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine.

In a more preferred aspect the invention provides the followingcompound:2-butoxy-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine.

Since the compounds of the present invention, in particular compounds offormula (I), are intended for use in pharmaceutical compositions, itwill be understood that they are each provided in substantially pureform, for example at least 50% pure, more suitably at least 75% pure andpreferably at least 95% pure (% are on a wt/wt basis). Impurepreparations of the compound of formula (I) may be used for preparingthe more pure forms used in pharmaceutical compositions. Although thepurity of intermediate compounds of the present invention is lesscritical, it will be readily understood that the substantially pure formis preferred as for the compounds of formula (I). Preferably, wheneverpossible, the compounds of the present invention are available incrystalline form.

When some of the compounds of this invention are allowed to crystalliseor are recrysallised from organic solvents, solvent of recrystallisationmay be present in the crystalline product. This invention includeswithin its scope such solvates. Similarly, some of the compounds of thisinvention may be crystallised or recrystallised from solvents containingwater. In such cases water of hydration may be formed. This inventionincludes within its scope stoichiometric hydrates as well as compoundscontaining variable amounts of water that may be produced by processessuch as lyophilisation. In addition, different crystallisationconditions may lead to the formation of different polymorphic forms ofcrystalline products. This invention includes within its scope all thepolymorphic forms of the compounds of formula (I).

Compounds of the invention are potent and selective inhibitors of COX-2.This activity is illustrated by their ability to selectively inhibitCOX-2 over COX-1.

In view of their selective COX-2 inhibitory activity, the compounds ofthe present invention are of interest for use in human and veterinarymedicine, particularly in the treatment of the pain (both chronic andacute), fever and inflammation of a variety of conditions and diseasesmediated by selective inhibition of COX-2. Such conditions and diseasesare well known in the art and include rheumatic fever; symptomsassociated with influenza or other viral infections, such as the commoncold; lower back and neck pain; headache; toothache; sprains andstrains; myositis; sympathetically maintained pain; synovitis;arthritis, including rheumatoid arthritis; degenerative joint diseases,including osteoarthritis; gout and ankylosing spondylitis; tendinitis;bursitis; skin related conditions, such as psoriasis, eczema, burns anddermatitis; injuries, such as sports injuries and those arising fromsurgical and dental procedures.

The compounds of the invention are also useful for the treatment ofneuropathic pain. Neuropathic pain syndromes can develop followingneuronal injury and the resulting pain may persist for months or years,even after the original injury has healed. Neuronal injury may occur inthe peripheral nerves, dorsal roots, spinal cord or certain regions inthe brain. Neuropathic pain syndromes are traditionally classifiedaccording to the disease or event that precipitated them. Neuropathicpain syndromes include: diabetic neuropathy; sciatica; non-specificlower back pain; multiple sclerosis pain; fibromyalgia; HIV-relatedneuropathy; neuralgia, such as post-herpetic neuralgia and trigeminalneuralgia; and pain resulting from physical trauma, amputation, cancer,toxins or chronic inflammatory conditions. These conditions aredifficult to treat and although several drugs are known to have limitedefficacy, complete pain control is rarely achieved. The symptoms ofneuropathic pain are incredibly heterogeneous and are often described asspontaneous shooting and lancinating pain, or ongoing, burning pain. Inaddition, there is pain associated with normally non-painful sensationssuch as “pins and needles” (paraesthesias and dysesthesias), increasedsensitivity to touch (hyperesthesia), painful sensation followinginnocuous stimulation (dynamic, static or thermal allodynia), increasedsensitivity to noxious stimuli (thermal, cold, mechanical hyperalgesia),continuing pain sensation after removal of the stimulation (hyperpathia)or an absence of or deficit in selective sensory pathways (hypoalgesia).

The compounds of the invention are also useful for the treatment ofother conditions mediated by selective inhibition of COX-2.

For example, the compounds of the invention inhibit cellular andneoplastic transformation and metastatic tumour growth and hence areuseful in the treatment of certain cancerous diseases, such as coloniccancer and prostate cancer. The compounds of the invention are alsouseful in reducing the number of adenomatous colorectal polyps and thusreduce the risk of developing colon cancer. The compounds of theinvention are also useful in the treatment of cancer associated withoverexpression of HER-2/neu, in particular breast cancer.

Compounds of the invention also prevent neuronal injury by inhibitingthe generation of neuronal free radicals (and hence oxidative stress)and therefore are of use in the treatment of stroke; epilepsy; andepileptic seizures (including grand mal, petit mal, myoclonic epilepsyand partial seizures).

Compounds of the invention also inhibit prostanoid-induced smooth musclecontraction and hence are of use in the treatment of dysmenorrhoea andpremature labour.

Compounds of the invention are also useful in the treatment of liverdisease, such as inflammatory liver disease, for example chronic viralhepatitis B, chronic viral hepatitis C, alcoholic liver injury, primarybiliary cirrhosis, autoimmune hepatitis, nonalcoholic steatohepatitisand liver transplant rejection.

Compounds of the invention inhibit inflammatory processes and thereforeare of use in the treatment of asthma, allergic rhinitis and respiratorydistress syndrome; gastrointestinal conditions such as inflammatorybowel disease, Crohn's disease, gastritis, irritable bowel syndrome andulcerative colitis; and the inflammation in such diseases as vasculardisease, migraine, periarteritis nodosa, thyroiditis, aplastic anaemia,Hodgkin's disease, sclerodoma, type I diabetes, myasthenia gravis,multiple sclerosis, sorcoidosis, nephrotic syndrome, Bechet's syndrome,polymyositis, gingivitis, conjunctivitis and myocardial ischemia.

Compounds of the invention are also useful in the treatment ofophthalmic diseases such as retinitis, retinopathies, uveitis and ofacute injury to the eye tissue.

Compounds of the invention are also useful for the treatment ofcognitive disorders such as dementia, particularly degenerative dementia(including senile dementia, Alzheimers disease, Pick's disease,Huntington's chorea, Parkinson's disease and Creutzfeldt-Jakob disease),and vascular dementia (including multi-infarct dementia), as well asdementia associated with intracranial space occupying lesions, trauma,infections and related conditions (including HIV infection), metabolism,toxins, anoxia and vitamin deficiency; and mild cognitive impairmentassociated with ageing, particularly Age Associated Memory Impairment.

Compounds of the invention are also useful in the treatment of disordersameliorated by a gastroprokinetic agent. Disorders ameliorated bygastroprokinetic agents include ileus, for example post-operative ileusand ileus during sepsis; gastroesophageal reflux disease (GORD, or itssynonym GERD); gastroparesis, such as diabetic gastroparesis; and otherfunctional bowel disorders, such as non-ulcerative dyspepsia (NUD) andnon-cardiac chest pain (NCCP).

According to a further aspect of the invention, we provide a compound offormula (I) for use in human or veterinary medicine.

According to another aspect of the invention, we provide a compound offormula (I) for use in the treatment of a condition which is mediated byCOX-2.

According to a further aspect of the invention, we provide a method oftreating a human or animal subject suffering from a condition which ismediated by COX-2 which comprises administering to said subject aneffective amount of a compound of formula (I).

According to a further aspect of the invention, we provide a method oftreating a human or animal subject suffering from an inflammatorydisorder, which method comprises administering to said subject aneffective amount of a compound of formula (I).

According to another aspect of the invention, we provide the use of acompound of formula (I) for the manufacture of a therapeutic agent forthe treatment of a condition which is mediated by COX-2.

According to another aspect of the invention, we provide the use of acompound of formula (I) for the manufacture of a therapeutic agent forthe treatment of an inflammatory disorder.

It is to be understood that reference to treatment includes bothtreatment of established symptoms and prophylactic treatment, unlessexplicitly stated otherwise.

It will be appreciated that the compounds of the invention mayadvantageously be used in conjunction with one or more other therapeuticagents. Examples of suitable agents for adjunctive therapy include a5HT₁ agonist, such as a triptan (e.g. sumatriptan or naratriptan); anadenosine A₁ agonist; an EP ligand; an NMDA modulator, such as a glycineantagonist; a sodium channel blocker (e.g. lamotrigine); a substance Pantagonist (e.g. an NK₁ antagonist); a cannabinoid; acetaminophen orphenacetin; a 5-lipoxygenase inhibitor; a leukotriene receptorantagonist; a DMARD (e.g. methotrexate); gabapentin and relatedcompounds; a tricyclic antidepressant (e.g. amitryptilline); a neuronestabilising antiepileptic drug; a mono-aminergic uptake inhibitor (e.g.venlafaxine); a matrix metalloproteinase inhibitor; a nitric oxidesynthase (NOS) inhibitor, such as an iNOS or an nNOS inhibitor; aninhibitor of the release, or action, of tumour necrosis factor α; anantibody therapy, such as a monoclonal antibody therapy; an antiviralagent, such as a nucleoside inhibitor (e.g. lamivudine) or an immunesystem modulator (e.g. interferon); an opioid analgesic; a localanaesthetic; a stimulant, including caffeine; an H₂-antagonist (e.g.ranitidine); a proton pump inhibitor (e.g. omeprazole); an antacid (e.g.aluminium or magnesium hydroxide; an antiflatulent (e.g. simethicone); adecongestant (e.g. phenylephrine, phenylpropanolamine, pseudoephedrine,oxymetazoline, epinephrine, naphazoline, xylometazoline,propylhexedrine, or levo-desoxyephedrine); an antitussive (e.g. codeine,hydrocodone, carmiphen, carbetapentane, or dextramethorphan); adiuretic; or a sedating or non-sedating antihistamine. It is to beunderstood that the present invention covers the use of a compound offormula (I) in combination with one or more other therapeutic agents.

The compounds of formula (I) are conveniently administered in the formof pharmaceutical compositions. Thus, in another aspect of theinvention, we provide a pharmaceutical composition comprising a compoundof formula (I) adapted for use in human or veterinary medicine. Suchcompositions may conveniently be presented for use in conventionalmanner in admixture with one or more physiologically acceptable carriersor excipients.

The compounds of formula (I) may be formulated for administration in anysuitable manner. They may, for example, be formulated for topicaladministration or administration by inhalation or, more preferably, fororal, transdermal or parenteral administration. The pharmaceuticalcomposition may be in a form such that it can effect controlled releaseof the compounds of formula (I).

For oral administration, the pharmaceutical composition may take theform of, for example, tablets (including sub-lingual tablets), capsules,powders, solutions, syrups or suspensions prepared by conventional meanswith acceptable excipients.

For transdermal administration, the pharmaceutical composition may begiven in the form of a transdermal patch, such as a transdermaliontophoretic patch.

For parenteral administration, the pharmaceutical composition may begiven as an injection or a continuous infusion (e.g. intravenously,intravascularly or subcutaneously). The compositions may take such formsas suspensions, solutions or emulsions in oily or aqueous vehicles andmay contain formulatory agents such as suspending, stabilising and/ordispersing agents. For administration by injection these may take theform of a unit dose presentation or as a multidose presentationpreferably with an added preservative.

Alternatively for parenteral administration the active ingredient may bein powder form for reconstitution with a suitable vehicle.

The compounds of the invention may also be formulated as a depotpreparation. Such long acting formulations may be administered byimplantation (for example subcutaneously or intramuscularly) or byintramuscular injection. Thus, for example, the compounds of theinvention may be formulated with suitable polymeric or hydrophobicmaterials (for example as an emulsion in an acceptable oil) or ionexchange resins, or as sparingly soluble derivatives, for example, as asparingly soluble salt.

As stated above, the compounds of the invention may also be used incombination with other therapeutic agents. The invention thus provides,in a further aspect, a combination comprising a compound of formula (I)together with a further therapeutic agent.

The combinations referred to above may conveniently be presented for usein the form of a pharmaceutical formulation and thus pharmaceuticalformulations comprising a combination as defined above together with apharmaceutically acceptable carrier or excipient comprise a furtheraspect of the invention. The individual components of such combinationsmay be administered either sequentially or simultaneously in separate orcombined pharmaceutical formulations.

When a compound of formula (I) is used in combination with a secondtherapeutic agent active against the same disease state the dose of eachcompound may differ from that when the compound is used alone.Appropriate doses will be readily appreciated by those skilled in theart.

A proposed daily dosage of a compound of formula (I) for the treatmentof man is 0.01 mg/kg to 500 mg/kg, such as 0.05 mg/kg to 100 mg/kg, e.g.0.1 mg/kg to 50 mg/kg, which may be conveniently administered in 1 to 4doses. The precise dose employed will depend on the age and condition ofthe patient and on the route of administration. Thus, for example, adaily dose of 0.25 mg/kg to 10 mg/kg may be suitable for systemicadministration.

Compounds of formula (I) may be prepared by any method known in the artfor the preparation of compounds of analogous structure.

Compounds of formula (I) may be prepared by a process which comprises:

-   reacting an alcohol R¹OH of formula (II) or a protected derivative    thereof with a compound of formula (III)    and thereafter and if necessary,-   interconverting a compound of formula (I) into another compound of    formula (I); and/or-   deprotecting a protected derivative of compound of formula (I).

The overall synthesis of a compound of formula (I) is shown in Scheme 1below in which, R¹ and R² are as defined in formula (I) above unlessotherwise stated, R³ is C₁₋₆alkyl; THF is tetrahydrofuran; MTBE ismethyl t-butyl ether; and alkyl is a straight or branched chain alkylgroup, for example a methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butylor t-butyl group.

Referring to Scheme 1, the preparation of compounds of formula (I) mayconveniently be achieved by the treatment of compounds of formula (III)with an alcohol of formula (II) in the presence of sodium hydride. Thereaction is conveniently carried out in a solvent such as THF and atbetween ambient temperature and reflux.

Conveniently the oxidation shown in Scheme 1 is effected using amonopersulfate compound, such as potassium peroxymonosulfate (known asOxone™) and the reaction is carried out in a solvent, such as an aqueousalcohol, (e.g. aqueous methanol), and at between −78° C. and ambienttemperature.

Alternatively, the oxidation shown in Scheme 1 may be effected usinghydrogen peroxide in the presence of catalytic sodium tungstatedihydrate. The reaction may be carried out in a solvent such as aceticacid and at between ambient temperature and reflux (e.g. 50° C.).

Referring to Scheme 1, the cyclisation of diones of formula (VI) to givethe corresponding pyrimidines of formula (IV) is conveniently carriedout employing a thioronium salt such as a 2-methyl-2-thiopseudoureasulfate and under reflux.

It will be appreciated by those skilled in the art that certain of theprocedures described in Scheme 1 for the preparation of compounds offormula (I) or intermediates thereto may not be applicable to some ofthe possible substituents.

It will be further appreciated by those skilled in the art that it maybe necessary or desirable to carry out the transformations described inScheme 1 in a different order from that described, or to modify one ormore of the transformations, to provide the desired compound of formula(I).

In one variation of Scheme 1, compounds of formula (III) wherein R³ isC₁₋₆alkyl or NH₂ may be prepared by oxidising a compound of formula(IV)A:

under oxidation conditions described hereinabove. Compounds of formula(IV)A may be prepared according to the general procedures of Scheme 1 byemploying sulphonyl derivatives in place of the corresponding sulfidecompounds of formulae (VI) and (VII).

It will be appreciated by those skilled in the art that compounds offormula (I) may be prepared by interconversion, utilising othercompounds of formula (I) as precursors. Suitable interconversions, suchas alkylations, are well known to those skilled in the art and aredescribed in many standard organic chemistry texts, such as ‘AdvancedOrganic Chemistry’ by Jerry March, fourth edition (Wiley, 1992),incorporated herein by reference. For example, compounds of formula (I)wherein R¹ is C₁₋₆alkyl, C₁₋₂alkyl substituted by one to five fluorineatoms, C₃₋₆alkenyl, C₃₋₆alkynyl, C₃₋₁₀cycloalkylC₀₋₆alkyl, C₄₋₁₂bridgedcycloalkane, A(CR⁴R⁵)_(n) (with the proviso that n is not zero) andB(CR⁴R⁵)_(n) may be prepared by alkylating the corresponding compound offormula (I) wherein R¹ is H.

Acylation of compounds of formula (I) wherein R³ is NH₂, to providecompounds of formula (I) wherein R³ is R⁷CONH, may be carried out byconventional means, for example by employing conventional acylatingagents such as those described in ‘Advanced Organic Chemistry’, pp417-424, incorporated herein by reference.

As will be appreciated by those skilled in the art it may be necessaryor desirable at any stage in the synthesis of compounds of formula (I)to protect one or more sensitive groups in the molecule so as to preventundesirable side reactions. The protecting groups used in thepreparation of compounds of formula (I) may be used in conventionalmanner. See, for example, those described in ‘Protective Groups inOrganic Synthesis’ by Theodora W Green and Peter G M Wuts, secondedition, (John Wiley and Sons, 1991), incorporated herein by reference,which also describes methods for the removal of such groups.

Alcohols of formula (II) are either known compounds or may be preparedby literature methods, such as those described in ‘Comprehensive OrganicTransformations: a guide to functional group preparations’ by RichardLarock (VCH, 1989), incorporated herein by reference.

Thioronium salts of formula (V) are either known compounds or may beprepared by literature methods, such as those described in A H Owens etal, Eur J Med Chem, 1988, 23(3), 295-300, incorporated herein byreference.

Acetophenones of formula (VII) are either known compounds or may beprepared by conventional chemistry.

Certain intermediates described above are novel compounds, and it is tobe understood that all novel intermediates herein form further aspectsof the present invention. Compounds of formulae (III) and (IV) are keyintermediates and represent a particular aspect of the presentinvention.

Solvates (e.g. hydrates) of a compound of the invention may be formedduring the work-up procedure of one of the aforementioned process steps.

The Intermediates and Examples that follow illustrate the invention butdo not limit the invention in any way. All temperatures are in ° C.Flash column chromatography was carried out using Merck 9385 silica.Solid Phase Extraction (SPE) chromatography was carried out using VarianMega Bond Elut (Si) cartridges (Anachem) under 15 mmHg vacuum. Thinlayer chromatography (Tlc) was carried out on silica plates. In additionto those already defined, the following abbreviations are used: Me,methyl; Ac, acyl; DMSO, dimethylsulphoxide; TFA, trifluoroacetic acid;DME, dimethoxyethane; DCM, dichloromethane; NMP, N-methyl pyrrolidone;and MTBE, methyl t-butyl ether.

Intermediate 1

4,4,4-Trifluoro-1-[4-(methylthio)phenyl]butane-1,3-dione

To a solution of ethyl trifluoroacetate (7.95 ml, 1.1eq) in MTBE (125ml) was added dropwise 25% sodium methoxide in methanol (16 ml, 1.2 eq).4-Methylthioacetophenone (Aldrich, 10 g, 0.06 mol) was added portionwiseand the mixture stirred at ambient temperature overnight. 2NHydrochloric acid (40 ml) was added cautiously and the organic phaseseparated, washed with brine and dried (Na₂SO₄) to give an orange solid.The orange solid was recrystallised from hot isopropanol to give thetitle compound as a yellow crystalline solid (11.25 g, 71%).

MH−261

Intermediate 2

2-(Methylthio)-4-[4-(methylthio)phenyl]-6-(trifluoromethyl) pyrimidine

To a mixture of 4,4,4-trifluoro-1-[4-(methylthio)phenyl]butane-1,3dione(5 g) and 2-methyl-2-thiopseudourea sulfate (5.1 g, 0.98 eq) in aceticacid (100 ml) was added sodium acetate (3 g, 2 eq) and heated underreflux for 8 h. The mixture was concentrated in vacuo and water (100 ml)added to give a solid, which was isolated by filtration to give thetitle compound as a yellow solid (5.8 g, quantitative).

MH+317

Intermediate 3

2-(Methylsulfonyl)-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine

To a solution of2-(methylthio)4-[4-(methylthio)phenyl]-6-(trifluoromethyl) pyrimidine(5.78 g) in MeOH (500 ml) was added a solution of OXONET (Aldrich, 56.23g, 5 eq) in water (200 ml). The mixture was stirred at ambienttemperature overnight, concentrated in vacuo and the residue partitionedbetween water and ethyl acetate (2×100 ml). The combined organic phaseswere dried and concentrated in vacuo to an off-white solid which wastriturated with hot isopropanol to give the title compound as a whitesolid (5.6 g, 80%).

MH+381

Tlc SiO₂ Ethyl acetate:cyclohexane (1:1) Rf 0.45

EXAMPLE 1

2-(4-Fluorophenoxy)-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine.

To a stirred solution of 4-fluorophenol (37 mg, 0.33 mmole) in drytetrahyrofuran (10 ml) was added, under an atmosphere of nitrogen,sodium hydride (60% dispersion in oil, 13 mg, 0.33 mmole) and theresulting mixture stirred at 20 for 30 min. To the stirred reactionmixture was added2-(methylsulfonyl)-4[4-(methylsulfonyl)phenyl]-6-trifluoromethyl)pyrimidine(114 mg, 0.33 mmole) in a single portion, and stirring was continued for2 h. The solvent was evaporated, and the residue partitioned betweendichloromethane and 2N sodium hydroxide. The dried organic phase wasevaporated to dryness. The residue was purified on a silica gel SPEcartridge eluting with chloroform to afford the title compound as acolourless solid (99 mg, 80%).

MH+413.

EXAMPLES 2 TO 10

Examples 2 to 10, as shown in Table 1 that follows, were prepared in themanner described for Example 1. TABLE 1 (I)

Ex R¹ R² R³ MS 2 3,4-difluorophenyl CF₃ CH₃ MH+ 431 3 4-methoxyphenylCF₃ CH₃ MH+ 425 4 4-fluorobenzyl CF₃ CH₃ MH+ 427 5 4-bromophenyl CF₃ CH₃MH+ 474 6 4-methylphenyl CF₃ CH₃ MH+ 409 7 5-chloropyridin-3-yl CF₃ CH₃MH+ 431 8 cyclohexyl CF₃ CH₃ MH+ 401 9 cyclopentylmethyl CF₃ CH₃ MH+ 40110 n-butyl CF₃ CH₃ MH+ 375

EXAMPLE 11

2-Butoxy-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine

Sodium methoxide (6.6 kg of a 30% w/w solution in methanol) was addedover at least 30 min to a solution of 4-(methylthio)acetophenone (5.0kg) and methyl trifluoroacetate (4.25 kg) in tert-butylmethylether (40L)at 40±3° C. The solution was heated at 40±3° C. for at least 3h. Aceticacid (55L) was added, followed by S-methyl 2-thiopseudourea sulfate(5.45 kg) and the mixture concentrated to ca. 45L. The mixture washeated at about 110° C. for at least a further 8 h (overnight) thenacetic acid (20 L) was added before cooling to 50±3° C. A solution ofsodium tungstate dihydrate (0.2 kg) in water (2.5L) was added, followedby hydrogen peroxide (20.7 kg of 30% w/v solution), which was added overat least 3 h, maintaining the temp at ca. 500. The mixture is heated atca. 50° C. for at least 12 h before cooling to 20±3° C. A solution ofsodium sulphite (3.45 kg) in water (28 L) was then added over at least30 min whilst maintaining the temperature at 20±3°. The mixture was agedat 20±3° C. for ca. 1 h and2-(methylsulfonyl)-4-[4(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidinecollected by filtration, washed with water (3×15L) and dried at up to600 in vacuo.

Yield, 9.96 kg, 90% of theory.

A suspension of2-(methylsulfonyl)[4-(methylsulfonyl)phenyl]-(trifluoromethyl)pyrimidine(525 g) in n-butanol (5.25 L) was treated with potassium carbonate (210g) at 20±5° C. The mixture was heated to 50±5° C. overnight until thereaction was complete by HPLC. Acetic acid (1.57 L) was added dropwise,to control any gas evolution, keeping the temperature at 50±5° C. Water(3.67 L) was then added over 30 min keeping the temperature at 50±5° C.to allow full crystallisation to occur. The slurry was then cooled to20-25° C. and aged for at least 1 hour. The resulting product was thenfiltered under vacuum and washed with a mixture of n-butanol (787 mL),acetic acid (236 mL), and water (551 mL) followed by water (2×1.57L).The product was then dried at up to ca50° C. under vacuum to yield thetitle compound. Yield, 457 g, 88.4% of theory. The title compound wasfound to be identical to that of Example 10.

¹H NMR (CDCl₃) δ: 8.33(2H, d, paradi-substituted CH); 8.11(2H, d,para-di-substituted CH); 7.70(1H, s, aromatic CH); 4.54(2H, t, butylCH₂); 3.12(3H, s, sulphone CH₃); 1.88(2H, m, butyl CH₂); 1.55(2H, m,butyl CH₂); 1.01(3H, t, butyl CH₃).

Biological Data

Cell Based Assay

Inhibitory activity against human COX-1 and COX-2 was assessed in COScells which had been stably transfected with cDNA for human COX-1 andhuman COX-2. 24 Hours prior to experiment, COS cells were transferredfrom the 175 cm² flasks in which they were grown, onto 24-well cellculture plates using the following procedure. The incubation medium(Dulbecco's modified eagles medium (DMEM) supplemented withheat-inactivated foetal calf serum (10% v/v), penicillin (100 IU/ml),streptomycin (100 μg/ml) and geneticin (600 μg/ml)) was removed from aflask of confluent cells (1 flask at confluency contains approximately1×10⁷ cells). 5 ml of phosphate buffered saline (PBS) was added to theflask to wash the cells. Having discarded the PBS, cells were thenincubated with 5 ml trypsin for 5 minutes in an incubator (37°). Theflask was then removed from the incubator and 5 ml of fresh incubationmedium was added. The contents of the flask was transferred to a 250 mlsterile container and the volume of incubation medium subsequently madeup to 100ml. 1 ml cell suspension was pipetted into each well of4×24-well cell culture plates. The plates were then placed in anincubator (37° C., 95% air/5% CO₂) overnight. If more than 1 flask ofcells were required, the cells from the individual flasks were combinedbefore being dispensed into the 24-well plates.

Following the overnight incubation, the incubation medium was completelyremoved from the 24-well cell culture plates and replaced with 250 μlfresh DMEM (37° C.). The test compounds were made up to 250× therequired test concentration in DMSO and were added to the wells in avolume of 1 μl. Plates were then mixed gently by swirling and thenplaced in an incubator for 1 hour (37° C., 95% air/5% CO₂). Followingthe incubation period, 10 μl of arachidonic acid (750 μM) was added toeach well to give a final arachidonic acid concentration of 30 μM.Plates were then incubated for a further 10 minutes, after which theincubation medium was removed from each well of the plates and stored at−20° C., prior to determination of prostaglandin E₂ (PGE2) levels usingenzyme immunoassay. The inhibitory potency of the test compound wasexpressed as an IC₅₀ value, which is defined as the concentration of thecompound required to inhibit the PGE2 release from the cells by 50%. Theselectivity ratio of inhibition of COX-1 versus COX-2 was calculated bycomparing respective IC₅₀ values.

The following IC₅₀ values for inhibition of COX-2 and COX-1 wereobtained from the cell based assay for compounds of the invention:Example No. COX-2: IC₅₀ (nM) COX-1: IC₅₀ (nM) 1 <1 81,300 2 23 9,675 3 42,923 5 6 61,380Microsomal Assay

Inhibitory activity against microsomal h-COX2 was assessed against amicrosomal preparation from baculovirus infected SF9 cells. An aliquotof microsomal preparation was thawed slowly on ice and a {fraction(1/40,000)} dilution prepared from it into the assay buffer (sterilewater, degassed with argon containing 100 mM HEPES (pH 7.4), 10 mM EDTA(pH7.4), 1 mM phenol, 1 mM reduced glutathione, 20 mg/ml gelatin and0.001 mM Hematin). Once diluted the enzyme solution was then sonicatedfor 5 seconds (Branson sonicator, setting 4, 1 cm tip) to ensure ahomogeneous suspension. 155 μl enzyme solution was then added to eachwell of a 96-well microtitre plate containing either 5 μl test compound(40× required test concentration) or 5 μl DMSO for controls. Plates werethen mixed and incubated at room temperature for 1 hour. Following theincubation period, 40 μl of 0.5 μM arachidonic acid was added to eachwell to give a final concentration of 0.1 μM. Plates were then mixed andincubated for exactly 10 minutes (room temperature) prior to addition of25 μM HCl (hydrochloric acid) to each well to stop the reaction. 25 μlof 1 M NaOH (sodium hydroxide) was then added to each well to neutralisethe solution prior to determination of PGE₂ levels by enzyme immunoassay(EIA).

The following IC₅₀ values for inhibition of COX-2 and COX-1 wereobtained from the microsomal assay for compounds of the invention:Example No. COX-2: IC₅₀ (nM) COX-1: IC₅₀ (nM) 6 <10 3,752 7 <10 79,889 8<10 1,860 9 22 69,000 10 22 >30000

1. A compound of formula (I)

in which: R¹ is selected from the group consisting of H, C₁₋₆alkyl,C₁₋₂alkyl substituted by one to five fluorine atoms, C₃₋₆alkenyl,C₃₋₆alkynyl, C₃₋₁₀cycloalkylC₀₋₆alkyl, C₄₋₁₂bridged cycloalkyl,A(CR⁴R⁵)_(n) and B(CR⁴R⁵)_(n); R² is C₁₋₂alkyl substituted by one tofive fluorine atoms; R³ is selected from the group consisting ofC₁₋₆alkyl, NH₂ and R⁷CONH; R⁴ and R⁵ are independently selected from Hor C₁₋₆alkyl; A is an unsubstituted 5- or 6-membered heteroaryl or anunsubstituted 6-membered aryl, or a 5- or 6-membered heteroaryl or a6-membered aryl substituted by one or more R⁶; R⁶ is selected from thegroup consisting of halogen, C₁₋₆alkyl, C₁₋₆alkyl substituted by onemore fluorine atoms, C₁₋₆alkoxy, C₁₋₆alkoxy substituted by one or moreF, NH₂SO₂ and C₁₋₆alkylSO₂; B is selected from the group consisting of

where

defines the point of attachment of the ring; R⁷ is selected from thegroup consisting of H, C₁₋₆alkyl, C₁₋₆alkoxy, C₁₋₆alkylOC₁₋₆alkyl,phenyl, HO₂CC₁₋₆alkyl, C₁₋₆alkylOCOC₁₋₆alkyl, C₁₋₆alkylOCO, H₂C₁₋₆alkyl,C₁₋₆alkylOCONHC₁₋₆alkyl and C₁₋₆alkylCONHC₁₋₆alkyl; and n is 0 to
 4. 2.The compound as claimed in claim 1 wherein R¹ is selected from the groupconsisting of C₁₋₆alkyl, C₁₋₂alkyl substituted by one to five fluorineatoms, C₃₋₁₀cycloalkylC₀₋₆alkyl and A(CR⁴R⁵)_(n).
 3. The compound asclaimed in claim 1 wherein R² is CHF₂, CH₂F or CF₃.
 4. The compound asclaimed in claim 1 wherein R³ is C₁₋₆alkyl.
 5. The compound as claimedin claim 1 wherein R⁴ and R⁵ are independently selected from H ormethyl.
 6. The compound as claimed in claim 1 wherein A is selected fromthe group consisting of

where

defines the point of attachment of the ring and A is unsubstituted orsubstituted by one or two R⁶.
 7. The compound as claimed in claim 1wherein R⁶ is selected from the group consisting of halogen, C₁₋₃alkyl,C₁₋₃alkyl substituted by one to three fluorine atoms, and C₁₋₃alkoxy. 8.The compound as claimed in claim 1 wherein R⁷ is selected from the groupconsisting of C₁₋₆alkyl, phenyl and aminomethyl.
 9. The compound asclaimed in claim 1 wherein n is 0 to
 2. 10. The compound as claimed inclaim 1 wherein R¹ is C₁₋₆alkyl; R² is CF₃; and R³ is C₁₋₆alkyl.
 11. Thecompound as claimed in claim 1 wherein R¹ is C₃₋₁₀cycloalkylC₀₋₆alkyl;R² is CF₃; and R³ is C₁₋₆alkyl.
 12. The compound as claimed in claim 1wherein R¹ is C₃₋₁₀cycloalkylmethyl; R² is CF₃; and R³ is C₁₋₆alkyl. 13.The compound as claimed in claim 1 wherein R¹ is A(CR⁴R⁵)_(n); R² isCF₃; R³ is methyl; R⁴ and R⁵ are both H; A is selected from the groupconsisting of

and A is unsubstituted or substituted by one or two R⁶; R⁶ is selectedfrom the group consisting of fluorine, chlorine, methyl, CF₃ andmethoxy; and n is 0 or
 1. 14. (Canceled.) 15.2-Butoxy-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine. 16.A process for the preparation of a compound as defined in claim 1, whichcomprises: (A), reacting an alcohol R¹OH of formula (II) or a protectedderivative thereof with a compound of formula (III)

and thereafter and if necessary, (B), interconverting a compound offormula (I) into another compound of formula (I); and/or (C),deprotecting a protected derivative of compound of formula (I).
 17. Apharmaceutical composition comprising a compound as defined in claim 1in admixture with one or more physiologically acceptable carriers orexcipients.
 18. (Canceled)
 19. A method of treating a subject sufferingfrom a condition which is mediated by COX-2 which comprisesadministering to said subject an effective amount of a compound asdefined in claim
 1. 20. A method of treating a subject suffering from aninflammatory disorder, which method comprises administering to saidsubject an effective amount of a compound as defined claim
 1. 21-22.(Canceled)
 23. A compound selected from2-(4-fluorophenoxy)-4-[4-(methylsulfonyl)phenyl]-6](trifluoromethyl)pyrimidine;2-(4-methoxyphenoxy)-4-[4-(methylsulfonyl)phenyl]-6-trifluoromethyl)pyrimidine;2-butoxy-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine;2-[(5-chloropyridin-3-yl)oxy]-4-[4-(methylsulfony)phenyl]-6-(trifluoromethyl)pyrimidine;and2-(cyclohexyloxy)-4-[4-(methylsulfonyl)phenyl]-6-(trifluoromethyl)pyrimidine.24. The method according to claim 19, wherein said subject is a human.25. The method according to claim 20, wherein said subject is a human.26. The compound according to claim 1, wherein R¹ is C₁₋₆alkyl; R² isCF₃; and R³ is C₁₋₃alkyl.
 27. The compound as claimed in claim 1 whereinR¹ is C₃₋₁₀cycloalkyl; R² is CF₃; and R³ is C₁₋₃alkyl.
 28. The compoundas claimed in claim 1 wherein R¹ is C₃₋₇cycloalkylmethyl; R² is CF₃; andR³ is C₁₋₃alkyl.